I presume this is a fairly new shotgun. Browning hand fits fits the locking bolt very tight to the barrel lug. On a new superposed the top lever normally does not return to a central position when the action is closed, it will eventually center as the locking bolt wears into position and the lever becomes easy to move. Be sure there is no "dirt" in the locking notches in the barrel. A teflon based lub will help.

Paulj

"a wise man learns by experience, a wiser man by the experience of others"